Improve in-memory exponent table creation #114
Conversation
|
Sigh, I don't know why this Maven plugin is failing. I will close and re-open this PR to cause a retest and see if that fixes it. |
| { | ||
| BigInteger value = ModPowAbstraction.modPow(element, BigInteger.valueOf(i), NSquared); | ||
| value = value.multiply(element).mod(NSquared); |
There was a problem hiding this comment.
Why was ModPowAbstraction removed here?
There was a problem hiding this comment.
... to avoid the need to compute the power of each big integer. The point of the PR is to just use multiplication.
For example, the code may be creating an expTable with 256 powers of a number of big integers.
In the current implementation using ModPowAbstration that is achieved by computing all 256 powers individually, i.e. element^0, element^1, ... element^255. Clearly as we build the table we know the value for (element-1)^n so we can simply remember the previous value and multiply it by element to find the next value.
This runs faster in my benchmarking.
Accumulate values in expTable rather than repeatedly compute powers.
Please take a look. This benches faster for me.